Method of producing thiocarbamates and thiocarbonates



United States l atent 055cc 3,161,666 Patented Dec. 15, 1964 3,161,666 4 METHOD OF PRODUCING TIHOCARBAMATES AND THIOCARBONATES Frank J. Sowa, Cranford,-NJ.- (305 E. 46th St, New York, N.Y.) No Drawing. Filed Aug. 30, 1961, Ser. No. 134,813 12 Claims. (Cl. 260-455) This application is a continuation-impart of co-pending application Serial No. 734,423, filed May 12, 1958, and now abandoned.

This invention relates to methods for producing thio carbamates and thiocarbonates and is directed particularly to reactions whereby a whole series of such compounds may be produced easily and economically.

In accordance with the methods described in co-pending application Serial No. 547,840, filed November 18, 1955, now Patent No. 2,834,799, carbamic and carbonate esters are produced by reactions between ureas and alcohols under the influence of boron trifiuoride.

It has now been found that substantially the same type of reaction can be carried out when employing boron tritiuoride or other deamminating agents when the re- :actants are ureas or thioureas and alkanols or mercaptans, at least one of which reactants contains sulfur. Those reactions which result in the formation of thiocarbarnates may be represented by the following typical equations:

where R and R are hydrogen, alkyl or aryl hydrocarbon radicals or chlorinated alkyl 'or aryl hydrocarbon radicals, n is an alkyl hydrocarbon radicaL'and n either an alkyl or an aryl hydrocarbon-radical or a chlorirnamd alkyl or aryl hydrocarbon, 'or a group contaiiiing -only carbon, hydrogen and sulfur. Those reactions which result in the formation of titlecarbonates may be represented by the following equations:

of thiocarbamates, tbiolcarbamates, dithiocarbamates, as well as thiolcarbonates and thiocarbonates.

It is further possible to use various sources of boron trifiuoride as deamminating agents in carrying out the foregoing reactions. For this purpose, such compounds as NH -BF NHgBF RO-BF or the urea bomb trifiuoride complexes of Patent No.2,980,733. In the alternative, such deamminating agents as zinc chloride, tin chloride, ferric chloride, phosphorous frichloride, cuprpus acetate and the like may be used. Neverthelessffor most purposes it is convenient to use gaseous boron trifluoride and to carry out the reaction in the presence of a liquid which may be a solvent for one or more of the reactants.

Accordingly, the principal object of the present invention is to provide novel methods for producing thiocarbamates and thiocarbonates.

Another object of the invention is to produce thiocarbamates and thiocarbonates under the influence of a deamrninating agent.

A specific object of the invention is to carry out such processes while using boron trifiuoride as the deamminating agent.

These and other objects and features of the present invention will appear from the following description thereof wherein typical methods and reactants are cited for the purpose of indicating the nature of the invention but without intending to limit the invention thereby.

In carrying out the methods of the presentinvention, substantially 'any tbiourea which an H N- group may be used and any mercaptan may be employed. Moreover, when reacting 'thioureas with alcohols, substantially any alkanol may be used, whereas, when re acting ureas with mercaptans, either urea itself or any of those substituted u'reas which contain an HgN- group may be employed. Thus, the nreas and which may be employed maybe represented by the formula where X is either sulfur or oxygen and R and R are itself and the monoand unsymmetrical disubstit11ted was such as monomethyl urea, unsymmetrical dimethyl urea, and the corresponding ethyl, propyl, butyl, cyclohexyl, phenyl, tolyl, naphthyl, and benzyl nr'easas well as the corresponding monoand polychlorinated alky'l-and aryl ureas. 7

Typical of the 'thiourea's which "may be employed are thiourea itself, monomethyl thiourea, unsymmetrical dimethyl thiourea, and the corresponding ethyl, propyl,

butyl, cyclohexyl, phenyl, tolyl, naphthyl, benzyl thio ureas and chlorinated alkyl and aryl thioureas such as monoand dichlorophenyl thiourea and dichloroethyl thiourea.

Among the alkanols which may be used are methyl, ethyl, propyl, butyl, octyl and stearyl alcohols for example.

Typical mercaptans which may be used in carrying out the process are methyl, ethyl, propyl, butyl, phenyl, tolyl or benzyl mercaptan as well as long chain mercaptans such as dodecyl mercaptan. It is also possible to use monoand polychlorinated alkyl and aryl mercaptans such as dichlorophenyl mercaptan or dichloroethyl mercaptan. Furthermore, dithio mercaptans such as 1,2-ethanedithio1 may be used.

In general when carrying out the methods of the present invention, the urea or thiourea is dissolved in a solvent such as an alcohol or liquid mercaptan or the reactants 3 may be dissolved or suspended in an inert liquid such as benzene or other hydrmarbon.

The reaction mixture is heated whereupon gaseous boron trifiuoride may be bubbled into the solution. When a source of boron trilluoride such as monoammino boron 5 trifluoride (NI-l -BF ammonium fluoborate (NH -BF or the complex urea 4-BF is used, it may be added to the mixture prior to heating. If other types of deathminating agents are used, they may be added either prior to or during the heating of the reaction mixture.

The temperature at which the reaction is carried out will depend upon the reactants employed and the end products to be obtained. Ordinarily, reaction temperatures of from 35 to 150 C. are employed in producing lower alkyl O-alkyl and S-alkyl carbamates and thiocarbarnates. However, when using long chain or high boiling reactants or gleamminating agents other than boron trifluoride, the temperature employed may be as high as 200 C. or more. However, it is found that some of the products formed during the reaction tend to decompose readily and under such circumstances, the reaction may be conducted under reduced pressure and correspondingly lower temperatures.

In order to illustrate typical procedures which may be employed in carrying out the present invention, the following examples are cited.

Example I 228 grams (3 mols) of thiourea were mixed with 420 grams (7 mols) of n-propanol and the mixture was heated to about 100 C. whereby all of the tbiourea was dissolved. 119 grams (1.76 mols) of boron trifluoride were then bubbled into the solution over a period of 2 hours. At this time, an insoluble liquid was formed and rose to the top of the reaction flask. When separated and distilled, it was identified as npropyl borate and distilled at about 172 to 175 C. The NH -BF which was formed and collected in the lower portion of the flask was separated by filtering the hot solution. The filtrate was cooled to about 15 C. for 3 hours whereby 152 grams of n-propyl thionocarbamate was recovered. The product had a melting point of 35 C. The NHyBF; recovered weighed 92 grams after washing with hot-npropanol and drying.

Examples II to V (V) n-Butylliquid at room temperature solid at 17 C.

' Example v1 158.1 grams (1 mol) of N-cyclohexyl-thiourea were mixed with 230.3 grams (5 mols) of ethyl alcohol and the mixture heated until the N-cyclohexyl thiourea dis solved. 67.8 (1 mol) of boron trifluoride was then bubbled into the solution over a period of about 2 hours. 98 grams of ethyl-N-cyclohexyl thionocarbamate were thereby obtained and found to have aymelting point of 50 C.

Example VII The general procedure of Example I was used but 380 grams (5 mols) of n-propyl mercaptan were employed instead of the n-propanol of Example I, whereas 180 grams (3 mols) of urea were used in place of the thiourea of Example I. Upon completion of the reaction, n-propyl thiolcarbamate having a melting point of 91 C. was isolated in a yield of 60% of theory.

4 Example VIII The process of Example VII was repeated substituting thiourea for the urea previously employed whereby a 63% yield of n-propyl dithiocarbamate was obtamed.

Example IX 170.5 grams (1 mol) of N-3-chlorophenylurea and 761.5 grams of l-propanethiol were added to a three liter, threenecked, round-bottomed flask fitted with a mechan ical stirrer, a reflux condenser and an inlet tube and thermometer.

Boron fluoride gas was added while stirring and mamtaining the temperature between 50 C. and 70 C. After 67 grams of boron fluoride had been adsorbed, the aghhtion was stopped and the contents refluxed for one hour.

The reaction mixture was cooled to room temperature, filtered to remove the ammonia-boron fluoride complex and the latter solid was extracted with hot propanol and filtered. The filtrates from above were combined and distilled to remove the propanol and l-propanethiol. The residue was recrystallized and proved to be propyl N-3- chlorophenylthiolcarbamate with a melting point of 78- C. The yield of I; capsular-Q was 200.6 grams (87% of theoretical).

The weight of ammonia-boron fluoride recovered was Example X Example XI 1375 grams 1' mol) of N,N-dipropylurea and 312s grams (6 mols) of ethanethiol was added to a three necked flask equipped as described-under Example 1X above. After adding 35 grams of anhydrous zinc chloride to'the reaction mixture, stirring was started while heating the contents by a heating mantel. As the temperature rose, 4

ammonia was evolved and the temperature range was be tween 30 C. and 70 C. Most o fthe amomniathat was formed combined with the excess ethanethiol and the ammonia. was evolved at higher temperatures by decomposition of this product. Some of the ethanethiol was evolved with the ammonia even though the temperature of the condenser was kept well below the boiling point of the ethanethiol. 1

The zinc chloride is removed from the reaction product by washing with dilute hydrochloric acid. The product was a liquid with an index of refraction of 1.4772 (25 C.) and density 0.958 (25 C.). The yield of product ethyl N,N-dipropylthiolcarbamate was 180 grams of theoretical).

By carrying out the processes described above but continuing the introduction of BF; into the reaction mixture until at least one molar equivalent of BF: based on the urea or thiourea used, it is found that alkyl thiocarbonates are formed. The yield of the carbonates increases as the amount of boron trifluoride used is increased until about 2 mol equivalents of the BE, have reacted.

The foregoing reactions are found to be general in character. Thus, by varying the alcohol or alkyl mercaptan and the urea or thiourea employed, the whole series of thioland tbionocarbonates can be produced as indicated by the equations Nos. 4 to 8 set forth above.

Example XII 60 grams (1 mol) of urea were added to 248 grams (4 mols) of ethyl mercaptan and gaseous boron trifluoride was bubbled into the reaction flask until 136 grams (2 mols) of BF}, had been taken up in the reaction. In this way, 109 grams of diethyl, dithiol carbonate were obtained which was a yellowish liquid having a boiling point of 196 C. The yield amounted to 65% of theory.

If desired, any of the carbamates produced in accordance with Examples 1- to VHI can be separated from the reaction mixture and mixed with an alkanol or a monoor dithio-mercaptan. The resulting mixture may then be further reacted with BF or another deamminating agent, as a separate operative step "to produce the desired thiocarbonate. It will, of course, be apparent that the carbamates employed in producing thiocarbonate compounds in accordance with the present invention may be produced by other methods or derived from any other source desired.

Example XIII 105.2 grams (1 mol) of ethyl thiolcarb'amate and 372.8 grams (6' mols) of ethyl mercaptan (ethanethiol) were weighed in a two liter, three-necked, round-bottomed flask. The flask was equipped with a mechanical stirrer,

reflux condenser and an inlet tube and thermometer in the third neck.

The contentswere stirred and boron fluoride was added slowly while maintaining the temperature between 35 50 C. After 68 grams of boron fluoride was added, the contents were refluxed for three hours.

After the contents had cooled to room temperature it was filtered. The ammonia-boron fluoride complex-..was washed with isopropyl alcohol and added to the filtrate. There was formed 83 grams of the solidammonia-boron fluoride complex.

The filtrate was distilled, first collecting the unreacted ethyl mercaptan and then the isopropyl alcohol. The residue was distilled under reduced pressure of 10 mm whereupon there was collected a main fraction boiling at around 90-100 C. which upon redistillation at atmospheric pressure distilled at 195 -l97 C. and was diethyl dithiolcarbonate I ribs- 04%) The yield of the diethyl dithiolcarbonate was 136 grams (90% of the theoretical).

Example XIV ll sHso (3-0 5 which distilled at so"'-6o c. mm).

In this way, substantially any of the thio type carbonates can be produced by simple reaction procedures depending upon the reactants selected for carrying out the process.

In general, as indicated above, the amount of the car bonates formed increases as the amount of the boron trifluoride or the other deamminating agent is increased. However, in most instan'ces, some of the-Barbonates are formed in producing the carbamates and, conversely, some of the carbamates may be present in the reaction mixture when forming the carbonates, particularly if the deamminating agent is less than two molar equivalents based on the amount of urea or thiourea employed. Nevertheless, it is generally possible to separate the end products by distillation, crystallization or other methods of purification.

In some instances, and particularly when using high 6 boiling reactants, the reaction mixture may be heated. On the other hand, the process is exothermic when gaseous boro trifiuon'de is used and the addition of further heat is seldom necessary. In fact, the reaction mixture often must be cooled to prevent loss of the end product by decomposition, rearrangement, or otherwise.

While the invention has been described above with particular reference to typical reactions and procedures, the examples cited have been chosen for the purpose of indicating the general nature of the application and are not intended to limit the scope of the invention.

I claim:

1. The method of producing a thio compound which is an ester of carbamic acid which comprises the steps of mixing together a compound having the formula HXR where X is selected from the group consisting of sulfur and oxygen and R is selected from the group consisting of alkyl and aryl hydrocarbon groups, monoand polychlorinated alkyl and aryl hydrocarbon groups and groups containing only hydrogen, carbon and sulfur, with a urea compound having the formula R R NiiNH,

where R and R are selected from the group consisting of hydrogen, alkyl and aryl hydrocarbon groups and monoand polychlorinated alkyl and aryl hydrocarbon groups, and X is selected from the group consisting of sulfur and oxygen one of which compounds in the mixture contains sulfur, and heating said mixture in the presence of not more than one mol of a deamminating agent selected from the group consisting of boron trifluoride, zinc chloride, tin chloride, ferric chloride phosphorous trichloride' and cuprous acetate, based on the weight of the urea compound employed.

2. The method of producing a thio compound which is an ester of carbonic acid which comprises the steps of mixing together a compound having the formula HXR where X is selected from the group consisting of sulfur and oxygen and R is selected from the group consisting of alkyl and aryl hydrocarbon groups, monoand polychlorinated alkyl and aryl hydrocarbon groups and groups containing only hydrogen, carbon and sulfur, with a urea compound having the formula where R and R are selected from the group consisting of hydrogen, alkyl and aryl hydrocarbon groups and monoand polychlorinated alkyl and aryl hydrocarbon groups, and X is selected item the group consisting of sulfur and oxygen one of which compounds in the mixture contains sulfur, and heating said mixture in the presence of a molar excess of a deamminating agent selected from the group consisting of boron trifluoride, zinc chloride, tin chloride, ferric chloride, phosphorous trichloride and cuprous acetate, based on the weight of the urea compound employed.

3. The method of producing a. thiocarbonate which comprises the steps of mixing a thiolcarbamate with a compound selected from the group consisting of an alkanol and monoand dithio mercaptans, and reacting a deamminating agent selected from the group consisting of boron trifluoride, zinc chloride, tin chloride, ferric chloride, phosphorous trichloride and cuprous acetate with the mixture at a temperature of about 35 C. to 200 C.

4. The method of producing a thiocarbonate which comprises the steps of mixing a thiolcarbamate with a compound selected from the group consisting of an alkanol and monoand dithio mercaptans, and reacting boron trifluoride with the mixture at a temperature of about 35 C. to 200 C.

5. The method of producing an alkylthio carbarnate which comprises reacting boron trifluoride with a mixture containing an alkyl mercaptan and urea while maintaining the reaction mixture at a temperature of about 35 C. to 200 C., the amount of boron tritiuoride used being not greater than the molar equivalent of the urea employed.

6. The method of producing an allryl thiouocarbamate which comprises reacting boron trifiuoride with a mirrture containing an allranol and thiourea while maintaining the reaction mixture at a temperature of about 35 C. to 200 C., the amount of said boron trifluoride used being not greater than the molar equivalent of the thiourea employed.

7. The method of producing an alkyl thionocarbarnate which comprises reacting a deamminating agent selected from the group consisting of boron trifluoride, zinc chlo ride, tin chloride, ferric chloride, phosphorous trichloride and cuprous acetate with a mixture containing an alltanol and thiourea, said thiourea containing an NH group and a hydrocarbon group, while maintaining the reaction mixture at a temperature of about 35 C. to 200 C., the amount of said deammiuating agent used being not greater than the molar equivalent of the thiourea employed, and thereafter separating the alkyl thionocarbamate produced from the reaction mixture.

8. The method of producing an alkyl thionocarbamate which comprises reacting boron trifiuoride with a mixture containing an alkanol and thiourea. said thiourea con taining an NH group and a hydrocarbon group, while maintaining the reaction mixture at a temperature of about 35 C. to 200 C., the amount of said boron tritiuoride used being not greater than the molar equivalent of the thiourea employed.

9. The method of producing an alkyl dithiocarbamate which comprises reacting boron trifluoride with a mixture containing an alkyl mercaptan and thiourea while main- 8 taining the reaction mixture at a temperature of about 35 C. to 200 C., the amount of said boron trifiuoride used being not greater than the molar equivalent of the thiourea employed.

10. The method of producing an alkyl dithiocarbamate which comprises reacting boron tritiuoride with a mix ture containing an alkyl mercaptan and thiourea, said thiourea containing an NH group and a hydrocarbon group, while maintaining the reaction mixture at a temperature of about 35 C. to 200 C., the amount of said boron tritiuoride used being not greater than the molar equivalent of the thiourea employed.

11. The method ofproducing alkylthio carbonates which comprises reacting boron trifluoride with a minture containing an alkyl mercaptan and urea while manntaining the reaction mixture at a temperature of about 35 C. to 200 C., and continuing the reaction until more than one molar equivalent of boron trifluoride based on the urea has been taken up in the reaction.

12. The method of producing an allcylthio thionocarbonate which comprises reacting boron u'ifluoride with a mixture containing an alkyl mercaptan and thiourea while maintaining the reaction mixture at a temperature of about 35 C. to 200 C. and continuing the reaction until more than one molar equivalent of the boron trifluoride based on the thiourea has been taken up in the reaction.

Wagner and look: Synthetic Organic Chemistry (1953),page 827. 

1. THE METHOD OF PRODUCING A THIO COMPOND WHICH IS AN ESTER OF CARBAMIC ACID WHICH COMPRISES THE STEPS OF MIXING TOGETHER A COMPOUND HAVING THE FORMULA HXR WHERE X IS SELECTED FROM THE GROUP CONSISTING OF SULFUR AND OXYGEN AND R IS SELECTED FROM THE GROUP CONSISTING OF ALKYL AND ARYL HYDROCARBON GROUPS, MONO- AND POLYCHLORINATED ALKYL AND ARYL HYDROCARBON GROUPS AND GROUPS CONTAINING ONLY HYDROGEN, CARBON AND SULFUR, WITH A UREA COMPOUND HAVING THE FORMULA 